1. Field of the Invention
The invention concerns a method for spatially resolved detection and display of movement processes in an examination subject by means of magnetic resonance tomography.
2. Description of the Prior Art
The detection and display of movement processes by means of magnetic resonance tomography is fundamentally known. For example, methods are available in order to detect the flow speed of the blood at many points of the body. These methods are differentiated into two groups according to the manner of the generation of the movement information. The first group deals with what are known as phase contrast (PC) methods, wherein movement information is imposed on the examination subject in the examination region via bipolar gradients. A flow speed can then be obtained via acquisition of multiple movement-coded image data sets and phase response or signal intensity curve determined from said image data sets.
“Time of flight” (TOF) methods are known as a second group. In these methods the magnetization is prepared at a point of the examination subject (for example by signal saturation) and read out at the same point or another point. A certain wait time passes between the preparation and the readout, based on which flow information can be achieved under consideration of the signal intensity of the image and possibly a difference calculation relative to a reference image.
It is known that phase contrast methods offer a better speed resolution, which is why these are preferably used for flow measurement.
A common factor in all conventional methods is that only one spatial direction can be flow-coded by such methods. The known methods also universally assume a laminar (thus uniform) flow.
Multiple methods are available to detect intestinal activity. For example, the position of a capsule in the intestine can be determined by means of capsule endoscopy, and the movement of the capsule (and thus of the intestine contents) can thus be indirectly inferred. Alternatively, the passage time of a substance through the intestine can be determined, with which an average speed can be established. Furthermore, it is known to repeatedly image the intestine diameter along the central axis of the intestine by means of magnetic resonance tomography in order to determine from this the intestinal peristalsis. To detect the intestine diameter it is therefore necessary to select the image orientation perpendicular to the central axis of the intestine. Since the intestine is known to run in multiple convolutions, only the acquisition of a small segment of the intestine is ever possible. These requirements also apply to the cited flow quantification method.